Rotary compressor



Feb. 9 H. A. FELDBUSH ROTARY COMPRESSOR Filed April 21, 1953 H A R RYA.- FE LDBUSH INVENTOR.

United States PatentO "ice ROTARY COMPRESSOR Harry A. Feldbush, ShortHills, N. J., assignor to Worthington Corporation, Hudson, N. 1., acorporation of Delaware Application April 21, 1953, Serial No. 350,091

Claims. (Cl. 230-158) This invention relates to rotary fluid compressorsembodying a rotor carrying sliding vanes which rotates in an off-centeror eccentric cylinder to compress the fluid, and more particular tomulti-stage compressors of this type which are substantially floodedwith oil or other suitable coolant to provide lubrication of thecompressor, maintenance of the compression temperature within desiredlimits and below the flash point of the lubricating oil or coolant toeliminate breakdown and carbonization as Well as reducing thecompression temperature to permit the maintaining of the temperature ofthe discharged compressed fluid within a desirable range, and also toprovide an efficient seal between the walls of the cylinder and thesliding vanes to provide high efliciency for such compressors.

More specifically, the present invention comprises a rotary compressorof the type specified wherein the high pressure rotor and the lowpressure rotor are arranged one to the other and one of the rotors isdriven directly from a prime mover through gearing or other suitablepower transmitting means thus making it possible to adjust any two-stagecompressor of a given length and diameter to a higher or lowercompression range than that for which it had been designed, by changingthe speed ratio only. Similarly, it is possible to run the highcompression stage of the compressor at different and more favorablespeeds than the low pressure stage and thereby increase the overallefliciency of the compressor and by running the two stages at differentspeeds it is possible to vary the discharge pressure of the compressorover a fairly wide range without adversely affecting the efliciency ofthe compressor.

Other advantages of the compressor of the present invention are: that bythe arrangement of the compressor stages in axially parallel relation acompressor of comparable capacity which is shorter in length than thoseembodying axially aligned stages is provided, as well as a compressor ofthe liquid-flooded type which is selfdraining, i. e., the air-fluidmixture flows downward and the flow is supported by gravity.

Compressors of this type are generally equipped with unloading valves,which permit unloading and loading of the compressor in accordance withdemand for pressure air, and an advantage of the present compressorstructure embodying the self-draining feature above referred to willpermit complete closure of the unloading va'lve which operation cannotbe resorted to in rotary compressors of this type which are notself-draining.

Another advantage is that under standstill conditions the liquid pumpwill be submerged in liquid and secure immediate suction from the veryfirst moment when the compressor is started, thus insuring instant andproper flow of coolant liquid during the operation of the unit.

With these and other objects in view, as may appear from theaccompanying specification, the invention consists of various featuresof construction and combination of parts, which will be first describedin connection with Patented Feb. 5, 1957 the accompanying drawings,showing a rotary compressor of a preferred form embodying the invention,and the features forming the invention will be specifically pointed outin the claims.

In the drawings:

Figure 1 is a side elevation of the improved compressor.

Figure 2 is a longitudinal section through the compressor taken on theline 22 of Figure 3.

Figure 3 is a vertical cross-section through the compressor taken on theline 3-3 of Figure 2.

Referring more particularly to the drawings, the improved compressorcomprises a multi-stage compressor having the low compression stageaxially parallel to and placed above the high compression stage 2 of thecompressor as clearly shown in Figures 2 and 3 of the drawings.

The low compression stage of the compressor comprises a housing 3 havingan inlet 4 through which the fluid to be compressed enters. The fluid tobe compressed is compressed by the rotor 5 which is rotatably mountedwithin the cylinder 3 eccentrically of the axis of the cylinder asclearly shown in Figure 3 of the drawings. In other words, the cylinderis oflset relative to the circumference of the rotor 5. The rotor 5carries a plurality of radially extending vanes 6 which are slidable ingrooves 7 formed in the rotor. This construction of sliding vane rotoris not new in compressors of this type and the operation of suchcompressors is that the vanes being thrown outwardly by centrifugalforce engage the inner wall of the cylinder 3 and form pockets betweenthe vanes which gradually increases in cross-sectional area for apredetermined distance after the pockets pass the inlet 4 to thecylinder. Between the inlet 4 and the discharge openings 7 of thecylinder the vanes move inwardly to decrease the cross-sectional area ofthe pockets thereby compressing the fluid and forcing the fluid at thehigher degree of compression outwardly through the discharge openings 7.

The cylinder 3 has an inlet fluid distributor 8 along the inlet to thecylinder which distributor is provided with a plurality of serrations orcutouts 9 to facilitate the proper distribution of the incoming fluidalong the rotor.

The rotor 5 is mounted upon a driving shaft 10 which is connected in anysuitable manner such as by the coupling 11 to a prime mover (not shown)and thus the rotor 5 of the low compression stage of the compressor isdriven directly from the prime mover.

The high compression stage 2 of the compressor includes the cylinder 12in which is mounted a rotor 13'. The rotor 13 is of the sameconstruction and operates in the same manner as the rotor 5 and it isdisposed in parallel axial relation with the rotor 5 and below the rotor5. The rotor 13 is rotated by means of a shaft 14 through the medium ofgears 15 and 16, the driving gear 15 being mounted upon the shaft 10 andthe driving gear 16 being mounted upon the shaft 14. The side 17 of thegear casing 18 enclosing the gears 15 and 16 is removable so that thegears 15 and 16 may be removed for changing the gear ratio andconsequently changing the speed of rotation of one of the rotors withrespect to the other. This gear drive construction and the placing ofthe rotors in parallel relation makes it possible to vary the ratio ofthe speed rotation between the two rotors as desired for varying thedischarge pressure of the compressor without adversely affecting thecompressor efiiciency and also permits the running of the rotor 13 ofthe high stage of compression at a different and more favorable speedthan the low pressure stage rotor 5 and thereby increase the overallefliciency of the compressor.

A liquid passage or conveying space 19 is provided between the dischargeopening 7 of the low pressure compression stage of the compressor andthe inlet openings of the high compression stage of the compressor isalso to provide thorough and adequate passage of the compressed fluidand coolant liquid from the first or low compression stage of thecompressor into the second or high compression stage.

A liquid pump structure 21 is connected to the cylinder 12 of the highcompression stage. While in the draw ings this pump is shown as of therotary gear type it is understood that any suitable type of pump may beprovided and it is driven by the shaft 1-1. The pump 21 has its inlet 22connected with any source of supply of lubrieating oil or coolant liquidwhich in a flooded compressor of the present type will be a reservoir(not shown) which receives the liquid from a separator (not shown) whichseparates the liquid from the compressed fluid after leaving thecompressor. Liquid pumped by the pump 21 is distributed through suitableconduits 24 to predetermined desirable points of the two stages of thecompressor and as shown in Figure 3 of the drawings some of this liquidis delivered directly into the cylinders 3 and 12 where it will serve tothoroughly lubricate the moving parts of the rotor, such as the sides ofthe vanes 6 and will form a fluid tight seal between the outer ends ofthe vanes 6 and the cylinder wall. This liquid will naturally under suchconditions become mixed with the fluid being compressed and will bedischarged through the discharge openings 7, conveying space 19 andinlets 20 into the second stage of the compressor where the fluid willbe compressed to a higher degree of compression. Further liquid will bemixed with the fluid as it is compressed in the high compression stageand this mixture will be discharged through the discharge openings 26into the discharge outlet 27 of the compressor.

By particular reference to Figure 3 of the drawings it will be notedthat the discharge openings 7, inlet openings 20 and discharge openings26 are all straight and substantially perpendicular so as to providedownward flow passages for the mixture of liquid and compressed fluidand thus the flow of this mixture through the compressor will be aidedby gravity and when the compressor is stopped or at a standstillcondition the liquid will drain downwardly into the lower cylinder 12where by the proper positioning of the reservoir (not shown) a liquidlevel will be maintained in the cylinder 12 and the pump 21 will alwaysbe flooded with liquid so that upon starting of the compressor liquidwill be instantly delivered to the various parts of the compressor.

While in the drawings gears are shown as the power transmission meansfrom one rotor to the other it is to be understood that any suitabletype of power transmission means may be employed and either the highpressure rotor or the low pressure rotor may be driven one from theother. Also the two stage cylinders may be arranged in any suitablerelation other than that shown in the drawings just so long as theself-draining relationship between them is maintained.

Lubricating oil, or any suitable liquid coolant solution, which willprovide cooling, sealing and lubrication of the compressor parts may beemployed for flooding the compressor.

It will be understood that the invention is not to be limited' to thespecific construction or arrangement of parts shown, but that they maybe widely modified within the invention defined by the claims.

What is claimed is:

1. In a flooded type rotary compressor utilizing lubricant fluid as thecooling medium for the fluid to be compressed, a low compression stageincluding a cylinder, a rotor eccentrically mounted therein, andslidable vanes carried by said low stage rotor, a high compression stageincluding a cylinder, a rotor eccentrically mounted therein, andslidable vanes carried by said high stage rotor, and means for rotatingsaid-rotors; said cylinders spaced from each other and in superposedparallel axial relation, op-

positely spaced walls between said cylinders, an interstage pressurefluid chamber formed by the outer surfaces of said cylinders and saidspaced walls, said low compression stage cylinder having a downwardlydisposed discharge opening communicating between a lower portion thereofand the interstage pressure fluid chamber and said high compressionstage cylinder having a downwardly disposed inlet opening communicatingbetween the lower portion of said interstage pressure fluid chamber andsaid high compression stage cylinder, said high compression stagecylinder having a downwardly disposed outlet means for conveyingcompressed fluid and to collect any accumulated cooling fluid from saidcompressor by gravity.

2. In a rotary compressor utilizing lubricant fluid as the coolingmedium for the fluid to be compressed, a low compression stage includinga cylinder, a rotor eccentrically mounted therein, and slidable vanescarried by said low stage rotor, a high compression stage including acylinder, a rotor eccentrically mounted therein, and slidable vanescarried by said high stage rotor, and means for rotating said rotors;means operated by said rotors and connected to said cylinders forintroducing a cooling fluid into the fluid to be compressed, saidcylinders spaced from each other and in superposed parallel axialrelation, oppositely spaced walls between said cylinders, an interstagepressure fluid chamber formed by the outer surfaces of said cylindersand said spaced walls, said iow compression stage cylinder having adownwardly disposed discharge opening communicating between a lowerportion thereof and the interstage pressure fluid chamber and said highcompression stage cylinder having a downwardly disposed inlet openingcommnicating between the lower portion of said interstage pressure fluidchamber and said high compression stage cylinder, said high compressionstage cylinder having a downwardly disposed outlet means for conveyingcompressed fluid and to collect any accumulated cooling from saidcompressor by gravity.

3. In a rotary compressor as claimed in claim 2 wherein means areprovided to rotate the rotors at different speeds.

4. In a flooded type rotary compressor utilizing lubricant fluid as thecooling medium for the fluid to be compressed, a low compression stageincluding a cylinder, a rotor eccentrically mounted therein and slidabievanes carried by sm'd low stage rotor, a high compression stageincluding a cylinder, a rotor eccentrically mounted therein, andslidable vanes carried by said high stage rotor, and means for rotatingsaid rotors; said cylinders spaced from each other and in superposedparallel axial relation, oppositely spaced walls between said cylinders,an interstage pressure fluid chamber formed by the outer surfaces ofsaid cylinders and said spaced walls, said low compression stagecylinder having a downwardly disposed discharge opening communicatingbetween a lower portion thereof and the interstage pressure fluidchamber and said high compression stage cylinder having a downwardlydisposed inlet opening communicating between the lower portion of saidinterstage pressure fluid chamber and said high compression stagecylinder, said high compression stage cylinder having an outlet meansfor conveying compressed fluid.

5. In a rotary compressor utilizing lubricant fluid as the coolingmedium for the fluid to be compressed, a low compression stage includinga cylinder, a rotor eccentrically mounted therein, and slidable vanescarried by said low stage rotor, a high compression stage including acylinder, a rotor eccentr'ically mounted therein, and slidable vanescarried by said high stage rotor, and means for rotating said rotors;means operated by said rotors and connected to said cylinders forintroducing a cooling fluid into the fluid to be compressed, saidcylinders spaced from each other and in superposed parallel axialrelation. oppositely spaced walls between said cylinders, an interstagepressure fluid chamber formed by the outer surfaces of said cylindersand said spaced walls,,said low compression stage cylinder having adownwardly disposed dis charge opening communicating between a lowerportion thereof and the in'terstage pressure fluid chamber and said highcompression stage cylinder having a downwardly disposed inlet openingcommunicating between the lower portion of said interstage pressurefluid chamber and said high compression stage cylinder, said highcompression stage cylinder having an outlet means for conveyingcompressed fluid.

2,126,279 Redfield Aug. 9, 1938 6 Hassler Jan. 2, Paget July 26, WhitelyFeb. 28, Vanni Sept. 5, Le Valley June 9, Ungar Oct. 12,

FOREIGN PATENTS Germany Feb. 12,

